Friction pumps



CCL 27, 1959 P. scHLUMBoHM FRrrc'rIoN PUMPS Filed May 2, 1955 Kw4-L Fig.4

United States Patent O FRICTION PUMPS Peter Schlumbohm, New York, N.Y.

Application May 2, 1955, Serial No. 505,341

1 Claim. (Cl. 230-127) The invention relates to a friction pump of thetype as described in my U.S. Patent 2,706,016. The inventionspecifically aims at a multi-stage friction pump. The invention isillustrated in Fig. 1 to Fig. 4 of the accompanying drawings by way ofexamples. In the friction pump described in the cited patent a pluralityof concentrically superposed porous discs is attached to a shaft and thespace between them forms the centrifugal space. lf the porous discs areof equal porosity a symmetrical configuration of a doubleconecharacterizes this impeller when rotating, due to the fact that withinthe impeller a given vacuum exists and that on the exterior side of bothporous discs the same atmospheric pressure prevails. I made where itleaves through valve controlmeans 13. As

the discovery that by applying discs of different porosity additionaleffects can be obtained.

The invention is illustrated in Fig. 1 to Fig. 4 of the accompanyingdrawings.

Fig. 1 shows as a side view, partly in vertical section, partly in view,an impeller comprising two discs arranged on a shaft.

Fig. 2 shows as a side view, partly in vertical section, partly in view,an impeller with three discs arranged on a shaft.

Fig. 3 shows diagrammatically, partly in vertical section, partly inView, and partly broken away, a multi-stage arrangement in which twofriction pumps are combined in line so that the exhaust of the iirstpump is fed to the intake of the second pump.

Fig. 4 shows diagrammatcally, partly in vertical section, partly inview, and partly broken away, a multi-stage arrangement in which sixfriction pumps are combined in line.

The impeller as shown in Fig. l comprises two discs 1, 2, arranged on ashaft 4 with a space 5 between them. If the disc 1 has a smallerporosity than the disc 2, more air will enter through disc 2 thanthrough disc 1. Y

-If disc 1 is impermeable and disc 2 is porous, no air will enterlthrough disc 1 and air will enter only through disc 2.

In the same manner a set of more than two discs will work out. If inFig. 2 disc 1 is less porous than the discs 2 and 3, more air will enterthrough discs 3 and V2 than will enter through disc 1. If such a set asshown in Fig. 1 and Fig. l2 runs in front of a co-pumping wall, theimpeller will be deected into the shape of a cone as shown in Fig. 3 andFig. 4. As shown in Fig. 3 and Fig. 4, the center of the co-pumping walladmits the gas or vapor to be pumped. The flow of the gas to be pumpedis controlled by Valve means 8 (in Fig. 3) or l2 (in Fig. 4) so that thedeflection of the impeller is maintained by the difference of pressurebetween the gas contacting disc 1 and the gas contacting the disc ordiscs adjacent to the copurnping wall. This means that the 360 nozzle 6which is formed between the edge of the impeller and the copumping wallwill adjust itself to the pressure conditions and will constitute a pathwhich allows only a one-way ow of the gas or vapor pumped fromvapor-zone P1 to vapor zone of higher pressure P2.

2,910,223 Patented Oct. 27, 1959 ICC This effect makes a multi-stagearrangement possible. As shown in Fig. 3, gas is fed from pressure zoneP2, controlled by pipe means 9 and valve means 10, into the intake ofthe next impeller which pumps this fluid into the zone of still higherpressure P3, from which it is discharged through pipe 11. The valvemeans are of the type of back-pressure control apparatus so that thevalve means open only if the pressure in the outgoing pipe is below acertain maximum. This means that the edge of the impeller will always beclose enough to the co-pumping wall to insure a one-way ilow throughthis 360 nozzle so that gas or vapor cannot backre from the zone of thehigher pressure P3 into the zone of pressure P2 nor from the zone of P2to the zone P1. g

In the arrangement of Fig. 4 six impellers are arranged on the sameshaft 4, the shaft being mounted in bearings 14, 15. The impellers arearranged within a casing 16 and the casing has partition walls 17 to 22.Each partition wall is the co-pumping wall o-f an impeller in thearrangement as shown and each partition wall has a center opening tofeed the centrifuging space between the outer disc 1 and the co-pumpingwall. Starting with the lowest pressure P1 on the intake side of thefirst impeller, this pressure is built up by the first impeller topressure P2, is further built up by the second impeller to pressure P3,etc., up to pressure P7 in the last chamber of casingA 16,

shown in Fig. 4, the openings in the various partition walls 17 to 22decrease in diameter. The largest opening is in partition wall 22 in thezone of the lowest pressure P1. This variation in the diameter of theopenings is a means of controlling the ow of the fluid which enters thecentrifuging space of the impeller.

F or use as impermeable impeller element such as disc 1 in Fig. 1, I usea material of a very smooth surface to re duce to a minimum the frictionwith the boundary layer of the -uid contacting it on the outside. Ifound it advantageous to use discs made from metal foil, waxpaper, ororganic foil.

Having now described the nature of my invention, and shown by way ofexamples the manner in which it may be performed,

I claim as my invention:

A centrifugal compressor comprising a casing having'- at smooth forwardand rear walls joined by a cylindrical wall to delne a pumping chamber,a centrifugal impeller mounted concentrically with the cylindrical wallfor rotation in said pumping chamber, said forward wall having a centralopening in said forward Wall, and said opening forming an intake to saidimpeller, said impeller comprising a plurality of flexible axiallyspaced discs, at least one of said discs being of porous constructionand having a forward and rear pumping surface, and one of said discsbeing of impermeable construction and having a forward pumping surface,the disc of porous construction being mounted closely adjacent to theforward flat wall of the casing to cooperate therewith to form a rstflow passage of uid beingl impelled by the forward surface of the porousdisc, and a second flow passage for fluid being pumped which passesthrough the porous disc, said passage being formed by the forwardsurface of the impermeable disc and the rearV surface of the porousdisc.

References Cited in the file of this patent UNITED STATES PATENTS2,632,598 Wales Mar. 24, 1953 2,655,310 Schlumbohm Oct. 14, 1953`2,706,016 Schlumbohm Apr. 12. 1955 2,739,757 Schlumbohm Mar. 27, 1956kFOREIGN PATENTS 9,314 Great Britain -..---......--.V-..--- of 1909

